The leghorn shouldn't go broody, the others might. It comes natural. I used to have rhode island reds and had one go broody, a guy at work who has raised hundreds of chickens told me they might, but wont do it right because the instinct has been breed out of them. He was right, none hatched. I recently learned there is some breeders of heritage (non-production) RIRs, even rose comb ones (extremely rare) that will go broody and raise chicks. I plan on getting some after the chickens I have now are done. I agree with you, why use an incubator, let the mom do the job, they know best. When I was little my father raised rose comb RIRs and he never segregated his chicks from the rest of the flock. The broody moms protected their chicks with the ferocity of the meanest rooster ever, and taught the chicks how to be chickens. The rooster would even help out, making funny noises when he found a goodie (worm bug etc.) and give it to the chicks to peck and eat. That guy at work that has hundreds of chickens, he keeps any broody ones he has and I think it was the barred rocks he said have been hatching his eggs at an old age for chickens, eight plus years old. I've thought about getting a cochin for setting. Bantams, especially silkies are suppose to be good at it also, but they are small. The best mom my father ever had was a black Japanese bantam, she must have laid her eggs in the woods because she would disappear every year (we would think she got ate) and reappear 21 days later with 18 to 21 chicks! She was the size of a small crow! And meaner than a wild cat when she had chicks! Lol! When we first got her she hatched out a nest of eggs, my father threw them in with one of the RIRs chicks and put a bunch of turkey eggs under her, she sat for another month! It was hilarious, watching them huge turkey polts following their tiny adopted mom around!
How old are your hens? Just wondering, if they're young you'll probably have to wait until spring to see what they do. If they're older, I wouldn't expect them to change their ways and suddenly start sitting. It can happen, but they get pretty set in their ways.
